Laser device, and exposure device and inspection device provided with laser device

Abstract

A laser device includes: a laser light output unit that outputs a fundamental wave laser light; a wavelength conversion unit that performs wavelength conversion of the fundamental wave laser light and outputs a converted laser light; an output detector that detects a power of the converted laser light; a power feedback circuit that controls the power of the fundamental wave laser light such that the power of the converted laser light is in constant; a phase matching adjustment configuration that adjusts a quantity of state at the wavelength conversion optical element; and a phase matching control circuit that controls an operation the phase matching adjustment configuration, wherein in a state that the power of the converted laser light is controlled in constant, the phase matching control circuit adjust the quantity of state in a predetermined range such that the power of the fundamental wave laser light is minimized.

The invention claimed is: 
     
       1. A laser device comprising:
 a laser light output unit that outputs a fundamental wave laser light; 
 a wavelength conversion unit that includes a wavelength conversion optical element, and that performs wavelength conversion of the fundamental wave laser light output from the laser light output unit and outputs a converted laser light; 
 an output detector that detects a power of the converted laser light output from the wavelength conversion unit; 
 a power feedback circuit that controls the power of the fundamental wave laser light output from the laser light output unit according to the power of the converted laser light detected by the output detector such that the power of the converted laser light output from the wavelength conversion unit is maintained in constant; 
 a phase matching adjustment configuration configured to adjust a quantity of state that relates to phase matching at the wavelength conversion optical element so as to satisfy a phase matching condition of the wavelength conversion optical element; and 
 a phase matching control circuit that controls setting of the quantity of state by the phase matching adjustment configuration, wherein 
 in a state in which the power of the converted laser light is controlled to be maintained in constant by the power feedback circuit, the phase matching control circuit instructs the phase matching adjustment configuration to adjust the quantity of state in a predetermined range such that the power of the fundamental wave laser light output from the laser light output unit is minimized. 
 
     
     
       2. The laser device according to  claim 1 , wherein
 assuming that a period of a control loop set for a power controlling of the converted laser light by the power feedback circuit as pa and that a period of fluctuation of the quantity of state by the phase matching adjustment configuration as pb, a relation pb≧4 pa holds true. 
 
     
     
       3. The laser device according to  claim 1 , further comprising a shift mechanism that shifts an incident position of the laser light input to the wavelength conversion optical element, wherein
 when the incident position of the laser light is shifted by the shift mechanism, the phase matching control circuit instructs the phase matching adjustment configuration to adjust the quantity of state. 
 
     
     
       4. The laser device according to  claim 1 , wherein:
 the quantity of state is a temperature of the wavelength conversion optical element; and 
 the phase matching adjustment configuration is a temperature adjustment device that adjusts the temperature of the wavelength conversion optical element. 
 
     
     
       5. The laser device according to  claim 4 , wherein
 a phase matching state at the wavelength conversion optical element is non-critical phase matching. 
 
     
     
       6. The laser device according to  claim 1 , wherein:
 the quantity of state is an incident angle of the laser light input to the wavelength conversion optical element; and 
 the phase matching adjustment configuration is an angle adjustment device that adjusts the incident angle. 
 
     
     
       7. An exposure device comprising:
 the laser device according to  claim 1 ; 
 a mask supporting unit that holds a photomask on which a predetermined exposure pattern is formed; 
 an exposure object supporting unit that holds an exposure object; 
 an illumination optical system that illuminates the photomask held by the mask support unit with the laser light output from the laser device; and 
 a projection optical system that projects a light transmitted through the photomask to the exposure object held by the exposure object supporting unit. 
 
     
     
       8. An inspection device comprising:
 the laser device according to  claim 1 ; 
 an inspection object supporting unit that holds an inspection object; 
 an illumination optical system that illuminates the inspection object held by the inspection object supporting unit with the laser light output from the laser device; and 
 a projection optical system that projects a light from the inspection object to a detector. 
 
     
     
       9. A laser device comprising:
 a laser light output unit that outputs a fundamental wave laser light; 
 a wavelength conversion unit that includes a wavelength conversion optical element, and that performs wavelength conversion of the laser light that inputs into the wavelength conversion optical element and outputs a converted laser light; 
 an output detection unit that detects a power of the converted laser light output from the wavelength conversion unit; 
 a power control unit that controls the power of the fundamental wave laser light output from the laser light output unit according to the power of the converted laser light; 
 a phase matching adjustment unit configured to adjust a quantity of state that relates to phase matching at the wavelength conversion optical element; and 
 a phase matching control unit that controls setting of the quantity of state by the phase matching adjustment unit, wherein 
 in a state in which the power of the converted laser light is controlled by the power control unit, the phase matching control unit instructs the phase matching adjustment unit to adjust the quantity of state such that the power of the fundamental wave laser light output from the laser light output unit is reduced towards a minimal value. 
 
     
     
       10. The laser device according to  claim 9 , wherein
 assuming that a period of a control loop set for a power controlling of the converted laser light by the power control unit as pa and that a period of fluctuation of the quantity of state by the phase matching adjustment unit as pb, a relation pb≧4 pa holds true. 
 
     
     
       11. The laser device according to  claim 9 , further comprising a shifting unit that shifts an incident position of the laser light input to the wavelength conversion optical element, wherein
 when the incident position of the laser light is shifted by the shifting unit, the phase matching control unit instructs the phase matching adjustment unit to adjust the quantity of state. 
 
     
     
       12. The laser device according to  claim 9 , wherein:
 the quantity of state is a temperature of the wavelength conversion optical element; and 
 the phase matching adjustment unit is a temperature adjustment device that adjusts the temperature of the wavelength conversion optical element. 
 
     
     
       13. The laser device according to  claim 12 , wherein
 a phase matching state at the wavelength conversion optical element is non-critical phase matching. 
 
     
     
       14. The laser device according to  claim 9 , wherein:
 the quantity of state is an incident angle of the laser light input to the wavelength conversion optical element; and 
 the phase matching adjustment unit is an angle adjustment device that adjusts the incident angle. 
 
     
     
       15. An exposure device comprising:
 the laser device according to  claim 9 ; 
 a mask supporting unit that holds a photomask on which a predetermined exposure pattern is formed; 
 an exposure object supporting unit that holds an exposure object; 
 an illumination optical system that illuminates the photomask held by the mask support unit with the laser light output from the laser device; and 
 a projection optical system that projects a light transmitted through the photomask to the exposure object held by the exposure object supporting unit. 
 
     
     
       16. An inspection device comprising:
 the laser device according to  claim 9 ; 
 an inspection object supporting unit that holds an inspection object; 
 an illumination optical system that illuminates the inspection object held by the inspection object supporting unit with the laser light output from the laser device; and 
 a projection optical system that projects a light from the inspection object to a detector.